Product category:
Miscellaneous machine tool equipment (fixtures, rotary tables etc.)
News Release from: NSK UK | Subject: Robust Series of spindle bearings
Edited by the Manufacturingtalk Editorial
Team on 06 August 2004
Roller bearing advances raise spindle
reliability
For modern machine tool spindles to operate reliably for extended periods under demanding acceleration, deceleration and higher speeds owes much to advances in rolling bearing technology.
The ability of modern machine tool spindles to operate reliably for extended periods under demanding acceleration/deceleration and higher speeds owes much to advances in rolling bearing technology over the last decade Central to these advances is materials technology, in particular the developments pioneered by manufacturers such as NSK to improve the purity of bearing steels
This article was originally published on Manufacturingtalk on 11 Jul 2008 at 8.00am (UK)
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The result of these developments is a range of new high performance steels, "Z", "EP" and "SHX" which provide one of the major elements in enabling NSK's ground-breaking Robust Series of spindle bearings to set new benchmarks for stable performance at ultra-high speeds, resistance to seizure and minimum levels of heat generation.
NSK's development of the new steels is the result of extensive research into the effects of non-metallic inclusions in the structure of high carbon bearing steel.
These affect the rolling fatigue life of the material adversely, leading to premature failure of bearings especially under demanding operating conditions.
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High-performance bearings maximise uptime
NSK's high-performance bearings provide extended uptime and reduced maintenance costs, despite operating conditions of extreme heat, water ingress, and lubricant contaminated with water and scale.
NSK has overcome this problem, achieving substantial reductions in non-metallic oxide inclusions with a new ultra clean steel making process.
Two of the results of this process are long life Z steel and EP steel.
Z Steel is NSK's standard material of manufacture for the new high speed Robust Series angular contact and cylindrical roller bearings.
Bearings made from this steel have a significantly extended service life when compared to conventional vacuum degassed steel, up to 1.8 times longer.
In addition, Z steel also benefits from more uniform response to heat treatment, a process that ensures good hardness and excellent wear resistance.
Offering even longer bearing life than Z steel, and up to three times that of conventional bearing materials, is NSK's EP steel.
EP steel is used as the material of manufacture for ball screw support bearings used in machine tool applications.
Bearings made from EP steel have increased reliability due to a new evaluation technique employed by NSK (NSK - ISD2).
The introduction of this technique into steel manufacturing technology resulted in a significant improvement in purity and reduction of non-metallic inclusions relative to Z steel.
EP steel has fewer large sized particles than Vacuum Arc Remelted (VAR) steel or conventionally refined Z steel.
For applications requiring even longer bearing life, 4 times that of standard SUJ2 (100Cr6/52100) steel bearings, NSK has produced SHX steel.
SHX steel integrates all the operating stability and low heat generation benefits of Z and EP steels, but with the added improvements of ultra-high speed operation -up to 3.5 x 106 dmN1 (i.e 41,000 rev/min for a 70mm bore bearing) and high resistance to seizure.
As such SHX steel is ideal as a bearing material for use in the latest generation of motorised machine tool spindles where abrupt changes and elevated temperatures greatly increase the possibility of bearing seizure.
Importantly, the heat resistance of SHX is nearly equal to that of M50 steel, a material which is used widely in bearings for jet engines, while its wear resistance, resistance to seizure and durability are all superior.
New Global Super Precision Bearing Catalogue - full details of the new Robust bearing system and NSK's other Super Precision range of bearing products are contained in a new global catalogue just produced by the company.
The new publication covers what is probably the largest range of Super Precision bearings available from any one manufacturer.
It supports spindle designers by simplifying the task of finding product and application information.
The catalogue also contains a section on spindle bearing selection with helpful explanations of spindle design.
(1 dmN is the bearing PCD in mm x spindle speed in rpm). Request a free brochure from NSK UK ...
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